1. Field of the Invention
This invention relates to boat propeller guards, and in particular to a boat propeller sled.
2. Background of the Invention
For some lime now, small boats have been powered by outboard motors. These small boats may include fishing boats, water ski boats, tour boats, and pleasure craft of all types. These outboard motor-powered boats generally range in size up to approximately twenty-five feet in length.
Outboard motor-equipped boats may be operated in fairly shallow water. One ever-present danger associated with operating boats in shallow water is the possibility of running the boat aground. This may occur where an un-anticipated sandbar is encountered, or perhaps an oyster bed. This can be hazardous to the boat occupants, or cause other problems, in a number of ways.
One danger is the boat occupants may be thrown overboard due to the sudden stop resulting from a boat abruptly running into a sand bar or oyster bed. Another problem may be damage to the outboard motor propeller: if the propeller strikes an oyster bed its rotation may be forced to stop against the urgings of the outboard motor, resulting in a damaged shear pin. If a shear pin is damaged, and no spare is available, then it may be impossible to change the propeller immediately.
If the boat has to be temporarily abandoned while a new shear pin is procured, a real danger exists that the boat could be stolen.
Another problem associated with current outboard motor design is that the propeller is sharp, and may rotate extremely quickly. Needless to say, this rapidly-spinning sharp propeller can present quite a hazard to swimmers and sea creatures in the vicinity of the propeller. Every year there are incidents of swimmers cut by outboard motor propellers, sometimes severely. And every year hundreds of underwater animals are injured, sometimes fatally, by outboard motor propellers. This problem is especially important where the injured animals are members of an endangered species such as manatees.
Still another problem which exists where a boat powered by an outboard motor runs aground, is that the boat may become seriously stuck on the underwater obstruction upon which it ran aground. Under these conditions, it may be impossible to free the boat short of procuring a tow from another power boat, or waiting for the tide to rise (if the boat has run aground near water under oceanic tidal influence). While modem outboard motor designs incorporate lower units which are generally curved at their lower forward edge, these lower units generally terminate in a sharp point at their lower rear corner. When an attempt to back a boat in too-shallow water is made, this sharp point tends to dig into the bottom, thus immobilizing the boat